st: Questions about -rspread-

Dear All,
I have two questions:
1. I've been trying to explore how -rspread- works. I gave a command and had
an output, but with the error message - invalid 'files' (198) - below the
output. The command was:
rspread welfare
The output looked alright, but I don't understand why the error message was
also generated. I've checked to be sure there are no zeros or missing
observations, using - count if mi(welfare) - and
- count if welfare==0 -. Each of the last two commands gave an ouput of 0.
Can anyone explain what the problem is?
2. Can -rspread- be used to generate two or more Lorenz curves within the
same axes?